Lubricant composition and use thereof

ABSTRACT

A lubricant composition comprising a base oil; at least one additive; and 0.001-10% by weight, based on the total weight of the lubricant composition, of an organic compound comprising both a polar moiety and a nonpolar moiety, as lubricity improver, wherein the organic compound has a relative permittivity ε r  in the range from 1.5 to 10, and a quotient ∫S 1 /∫S 2  for the organic compound is in the range from 1 to 25, wherein ∫S 1  denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm −1  in an ATR spectrum of the organic compound, and ∫S 2  denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm −1  in an ATR spectrum of the organic compound.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2021/060351, filed on Apr. 21, 2021, and claims benefit to German Patent Application No. DE 10 2020 111 392.7, filed on Apr. 27, 2020. The International Application was published in German on Nov. 4, 2021 as WO 2021/219455 under PCT Article 21(2).

FIELD

The present invention relates to lubricant compositions and to the use thereof as gear oil, roller bearing oil and slide bearing oil for industry in general and as gear oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

BACKGROUND

The challenge when lubricants or lubricant compositions are employed as gear oil, roller bearing oil and slide bearing oil for industry in general is to assure both very good tribological properties in the interdigitation and very good compatibility of the lubricant with respect to seal materials. In transmissions, slide bearings and roller bearings, in general, radial shaft sealing rings that are typically manufactured from elastomers such as FKM (fluoro rubber), NBR (nitrile-butadiene rubber), HNBR (hydrogenated nitrile-butadiene rubber), ACM/AEM (acrylate elastomers/ethylene acrylic elastomers) and polyurethanes are used. The importance of the seal compatibility of the lubricant is illustrated by the frequency of the causes of gear, slide bearing and roller bearing failures. The proportion of gear, slide bearing and roller bearing failures caused by the incompatibility of lubricant and seal material is significantly higher than a proportion of gear, slide bearing and roller bearing failures caused by wear, for example. Therefore, the selection of the base oil component(s) for the lubricant and carefully matched selection of additives is essential in order to prevent damage to seal materials and nevertheless to achieve very good tribological properties. A further problem is that many lubricants that are used in industry in general are unsuitable for occasional unintentional contact with foodstuffs, for example in the case of food applications; in other words, they do not have H1 certification under the NSF Code of Federal Regulations § 21 CFR 178.3570.

There is therefore a need for novel lubricants or lubricant compositions for use as gear oil, roller bearing oil or slide bearing oil for industry in general that show high compatibility with respect to seal materials, especially elastomer materials, and simultaneously have good tribological properties, such that they bring about an improvement in sliding characteristics, a reduction in the stick-slip effect, especially in the case of friction contact at high load and low speed, and a positive influence on micropitting load-carrying capacity.

Moreover, it would be desirable in practice if these lubricant compositions also have minimal toxicity and are permissible under NSF/H1 certification for occasional unintentional contact with foodstuffs, such that they are suitable for applications in the food processing industry.

In applications of lubricants or lubricant compositions in the marine sector and in inland waterways, i.e. applications in which the lubricants or lubricant compositions are typically used below the waterline in oil-to-water interfaces, there is the risk that the marine or water body environment is contaminated by escape of lubricant, caused by leaks for example. Even though attempts are made to seal the water side as well as possible in these applications, losses of lubricant are an everyday occurrence. There is therefore an enormous increase in demand for environmentally benign lubricants for reduction of pollution of the seas and inland waterways by chemicals. However, there is also an increase in demand for environmentally benign lubricants on land since the pollution of soils by chemicals is also becoming ever more important. Components that find use on land can come into contact with water, for example, as a result of rain. Moreover, leaks are not impossible here either, and so it can be contamination of the environment and of the soil. There is a high demand for environmentally benign lubricants on land particularly in the mining industry, in wind turbines and in agricultural machinery.

In the last few years, protection of the environment has become ever more significant, especially also the protection of the seas. For lubricants that are used below the waterline in oil-to-water interfaces, for example, the Vessel General Permit (VGP) from the United States Environmental Protection Agency, requires the use of “Environmentally Acceptable Lubricants (EALs)”, which must meet high demands with regard to biodegradability and aquatoxicity. EALs in common use are therefore produced on the basis of natural and synthetic esters, rather than on the basis of mineral oil as is conventional. By comparison with mineral-based lubricants, however, when EALs are used, on account of their comparatively low stability, there is frequently damage to seal materials and severe loss of performance with regard to sliding or lubrication characteristics.

There is therefore also a need for biocompatible lubricants, i.e. those having good biodegradability and minimal aquatoxicity, that have high compatibility with respect to seal materials, especially elastomer materials, especially for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways. This also includes use in machines and machine elements on land that may come into contact with water and/or aqueous media.

By comparison with mineral oil-based lubricants, moreover, when EALs are used, there is an increased frequency of problems in stem tube lubrication. There are many indications that, when EALs are used, there is inadequate lubrication of the bearing at low speeds and high load. It is known that states of inadequate lubrication can also occur at further lubrication sites. These include, for example, all slide bearings, gears, linear guides, pneumatic components, instruments, roller bearings, chains, cables, springs and propellers. In this connection, there is also a need for novel biocompatible lubricants for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, which additionally bring about an improvement in sliding characteristics.

SUMMARY

In an aspect, disclosed is a lubricant composition comprising a base oil; at least one additive; and 0.001-10% by weight, based on the total weight of the lubricant composition, of an organic compound comprising both a polar moiety and a nonpolar moiety, as lubricity improver, wherein the organic compound has a relative permittivity ε_(r) in the range from 1.5 to 10, and a quotient ∫S₁/∫S₂ for the organic compound is in the range from 1 to 25, wherein ∫S₁ denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and ∫S₂ denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm⁻¹ in an ATR spectrum of the organic compound.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:

FIG. 1 is a line graph showing the measurement of the Stribeck curves for a base formulation without lubricity improver and a lubricant of the invention with lubricity improver.

FIG. 2 is a bar graph showing the transition speed of all lubricants tested.

FIGS. 3A, 3B, 3C and 3D are line graphs showing a plot of coefficient of friction over time.

FIGS. 4A and 4B are bar graphs showing elastomer wear.

FIG. 5A is a bar graph showing weight loss.

FIG. 5B is a bar graph showing change in wear scar width.

DETAILED DESCRIPTION

It was therefore an object of the present invention to provide lubricants or lubricant compositions that show improved compatibility with respect to seal materials, especially elastomers, and have excellent tribological properties, such that they bring about improved sliding characteristics, a reduction in the stick-slip effect and a positive influence on micropitting load-carrying capacity, and are suitable for use as gear oil, roller bearing oil and slide bearing oil for industry in general.

It was a further object of the present invention to provide minimally toxic, i.e. NSF/H1-certified lubricants, which are suitable for use as gear oil, roller bearing oil and slide bearing oil for industry in general, including applications in the food processing industry, and which likewise show the aforementioned advantageous properties with regard to seal compatibility and sliding characteristics.

It was additionally an object of the present invention to provide biocompatible lubricants, i.e. those having good biodegradability and minimal aquatoxicity, which bring about improved compatibility with respect to seal materials, especially elastomers, and at the same time bring about an improvement in sliding or lubrication characteristics, and which are suitable for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

One or more of the aforementioned objects are achieved by a lubricant composition comprising, as constituents:

A) a base oil;

B) at least one additive; and

C) 0.001-10% by weight, based on the total weight of the lubricant composition, of an organic compound comprising both a polar moiety and a nonpolar moiety, as lubricity improver,

wherein the organic compound has a relative permittivity ε_(r) in the range from 1.5 to 10, and wherein a quotient ∫S₁/∫S₂ for the organic compound is in the range from 1 to 25,

“∫S₁” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and

“∫S₂” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm⁻¹ in an ATR spectrum of the organic compound.

It has been found that, surprisingly, the presence of an organic compound in addition to the further constituents/components present in the lubricant composition, where the organic compound comprises both a polar moiety and a nonpolar moiety and meets the requirements both on relative permittivity ε_(r) (in the range from 1.5 to 10) and on the quotient ∫S₁/∫S₂ (in the range from 1 to 25), brings about a significant improvement in sliding characteristics between two friction partners, for example metal/metal or metal/elastomer (e.g. FKM or NBR). The organic compound is therefore referred to herein as “lubrication improver”.

In the context of the invention, the terms “lubricant composition”, “lubricant” and “formulation” are used synonymously.

In the context of the present invention, the term “organic compound” includes both single compounds (i.e. molecules) and mixtures of single compounds, and also oligomers and polymers including homopolymers, copolymers and polymer blends, and mixtures thereof.

An oligomer in the context of the invention is understood to mean a molecule or chemical compound formed from a multitude of, especially two to ten, structurally identical or similar organic units (monomers) and especially having a weight-average molar mass (MW) up to about 1000. A polymer (homopolymer) in the context of the invention is accordingly understood to mean a molecule or chemical compound formed from a high number, especially more than ten, structurally identical or similar organic units (monomers) and especially having a weight-average molar mass (Mw) of about 1000 or more. A copolymer is understood to mean polymers composed of two or more different types of monomer unit.

According to the invention, the organic compound C) contains both a polar moiety and a nonpolar moiety, meaning that it is formed from one or more identical or different polar molecular moieties and one or more identical or different nonpolar molecular moieties, which results in a particular relative polarity. Polar molecular moieties in the context of the invention may be any polar functional groups known to the person skilled in the art. In particular, the polar molecular moieties are selected from one or more from a carbonyl group, ester group (R—CO—O—R), keto group (R—CO—R), aldehyde group (R—CHO), amide group (R—CO-A, A=NH₂, NHR, or NR₂), imide group (R—CO—NR—CO—R), carboxylic anhydride group (R—CO—O—CO—R), urea group (R₂N—CO—NR₂), urethane group (R—NH—CO—O—R), carboxylate group (R—COO—) and a carboxyl group (R—COOH), where R in each case independently represents any organic, aliphatic or aromatic radical. Nonpolar molecular moieties in the context of the invention may be any nonpolar groups known to the person skilled in the art, and they are especially selected from one or more from linear or branched or cyclic alkyl groups or aromatic groups, for example linear or branched alkylbenzene groups.

According to the invention, the organic compound C) has a relative permittivity ε_(r) in the range from 1.5 to 10, preferably from 1.7 to 8, especially preferably from 2 to 7, and most preferably from 2.3 to 5.

The relative permittivity ε_(r) of a medium, also called permittivity or dielectric constant, is the dimensionless ratio of its permittivity ε to the permittivity ε₀ of the vacuum: ε_(r)=ε/ε₀. Permittivity, also called dielectric conductivity, refers to a material property of electrically insulating polar or nonpolar substances, called dielectrics, and indicates the permeability of a material or substance to electrical fields. Relative permittivity is a measure of the field-attenuating effects of the dielectric polarization of the material or substance.

The organic compound C) present in accordance with the invention in the lubricant composition is additionally characterized in that it has a quotient ∫S₁/∫S₂ in the range from 1 to 25, preferably from 1.3 to 22, especially preferably 1.7 to 17, and most preferably from 2 to 14.

In this context, “∫S₁” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and “∫S₂” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm⁻¹ in an ATR spectrum of the organic compound.

It is known to the person skilled in the art that ATR infrared spectroscopy is an analytical technique in infrared spectroscopy which is suitable for solid and liquid samples and is now the dominant IR methodology in many fields. By contrast with the conventional IR analysis method, in which the transmittance of a sample is measured, ATR infrared spectroscopy is based on the principle of total reflection (ATR, attenuated total reflection, see N. J. Harrick: Internal Reflection Spectroscopy. John Wiley & Sons Inc, 1967, ISBN 0-470-35250-7). This results in similar spectra to those in transmission spectroscopy. Although the IR absorption bands in ATR spectra are broader and more intense toward greater wavelengths (smaller wavenumber) than in the case of corresponding transmission spectra, it is known that the positions of the IR absorption bands in transmission and ATR spectra are identical. It is known to the person skilled in the art from databases of spectra and tables of vibration data of important groups of atoms (e.g. Helmut Günzler, Hans-Ulrich Gremlich: IR-Spektroskopie: Eine Einführung [IR Spectroscopy: An Introduction], 4th edition. Wiley-VCH, Weinheim 2003, p. 165-240) that, in a transmission or ATR spectrum, particularly the characteristic IR absorption band of the C—O stretch vibration (valency vibration) of the carbonyl group of carbonyl compounds lies in the wavenumber range of about 1800-1650 cm⁻¹, and that, in a transmission or ATR spectrum, particularly the characteristic IR absorption band of the C—H stretch vibration (valence vibration) of a —C—H_(x) group (x=1, 2 or 3, number of bound hydrogen atoms) in aliphatic or aromatic hydrocarbons lies in the wavenumber range of about 3100-2750 cm⁻¹.

The quotient ∫S₁/∫S₂ thus expresses the absorption in the wavenumber range of 3100-2750 cm⁻¹, caused predominantly by nonpolar molecular moieties of the organic compound, relative to the absorption in the wavenumber range of 1800-1650 cm⁻¹, caused predominantly by polar molecular moieties of the organic compound. The quotient ∫S₁/∫S₂ can thus be interpreted as a measure of the polarity of the organic compound present in the lubricant composition that comprises both a polar moiety and a nonpolar moiety.

The amount of the organic compound C) in the lubricant composition is preferably 0.001% by weight or more, more preferably 0.05% by weight or more, for example 0.1% by weight or more, and 10% by weight or less, more preferably 5% by weight or less, based on the total weight of the lubricant composition, in order to achieve optimal elastomer compatibility and lubricity.

For example, in embodiments of the invention that are suitable for occasional unintentional contact with food, especially for use as gear oil, roller bearing oil and slide bearing oil for industry in general, including in the field of the food processing industry, it is particularly preferable when the amount of the organic compound C) is 0.001-2.5% by weight, and even more preferably 0.05-1% by weight, based on the total weight of the lubricant composition, in order to achieve optimal elastomer compatibility and lubricity.

For example, in embodiments of the invention that are suitable particularly for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, it is particularly preferable when the amount of the organic compound C) is 0.1-10% by weight, even more preferably 0.1-5% by weight, and most preferably 0.1-3% by weight, based on the total weight of the lubricant composition, in order to achieve optimal elastomer compatibility and lubricity.

By virtue of the addition of the organic compound that comprises both a polar moiety and a nonpolar moiety and meets the above-defined demands both on relative permittivity ε_(r) (in the range from 1.5 to 10) and on the quotient ∫S₁/∫S₂ (in the range from 1 to 25), in addition to the other components/constituents of the lubricant composition, such as base oil(s) or additive(s), it is surprisingly possible to achieve an improvement in sliding or lubrication characteristics, especially also in the case of low gear and bearing speeds and high load. Furthermore, the organic compound contributes to an improvement in the compatibility of the lubricant composition of the invention with respect to elastomer materials, such as FKM and NBR.

In one embodiment of the invention, the organic compounds C) additionally have NSF/H1 certification, such that they are used in lubricants that are employed in the food processing industry as gear oil, roller bearing oil and slide bearing oil for occasional unintentional contact with food.

In a further embodiment of the invention, the organic compound C) is an organic compound which is additionally biodegradable (for example according to OECD Test Guideline 301 A-F or OECD 306) and/or has low aquatoxicity (for example according to OECD Test Guideline 201, 202, 203 or 236). As a result, the organic compound is suitable for use in lubricants that are employed as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

Preferred examples of organic compounds that can advantageously be used as lubrication improver in the lubricant composition of the invention are, but are not limited to, the following compounds: maleic acid-olefin copolymers (commercially available, for example, as Ketjenlube® 135, Ketjenlube® 2700, Ketjenlube® 23000); modified polyesters (commercially available, for example, as Perfad™ 3000, Perfadm 3050); polymethylmethacrylate (PMMA), linear polymers and star polymers (commercially available, for example, as Lubrizol 87725); oleic acid, especially mixtures of C16-C18 fatty acids and C18 unsaturated fatty acids (commercially available, for example, as Herwemag OA); glycerol monooleates (GMO), especially those with a mono content of min. 40%, free glycerol max. 6% (commercially available, for example, as Ilco Lube 2316); polymethacrylate (PMA), linear polymers and comb polymers (commercially available, for example, as Viscoplex® 3-200); comb polymers of 1-decene and 9-dodecyl acid methyl ester (commercially available, for example, as Elevance Aria® WTP 40); pentaerythritol tetraisostearate (commercially available, for example, as Priolube™ 3987-LQ).

The lubricant composition of the invention comprises a base oil component as further constituent A).

The base oil is preferably selected from synthetic esters, especially neopentyl glycol esters such as neopentyl glycol diisostearate, pentaerythritol esters such as pentaerythritol tetraisostearate, trimethylolpropane esters such as trimethylolpropane trioleate or trimethylolpropane tricaprylate, pentaerythritol and trimethylolpropane complex esters that have preferably been fully esterified or partly esterified in any mixture with saturated and/or mono- or polyunsaturated monocarboxylic acids and/or dicarboxylic acids of chain length 4 to 36 carbon atoms, which may be linear or branched, such as pentaerythritol isostearate sebacate complex esters or trimethylolpropane isostearate stearate sebacate complex esters, aliphatic carboxylic and dicarboxylic esters such as di(2-ethylhexyl) sebacate, diisotridecyl adipate (DITA) or isopropyl oleate, triglyceride fatty acid (C8/C10) esters, trimellitic and pyromellitic esters, and estolides; hydrocarbons, especially polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, mineral oils, alkylnaphthalenes, ethylene/α-olefin oligomers, and farnesene-based oils; ether compounds, especially polyether polyols, perfluoropolyethers (PFPE), alkyl diphenyl ethers, and polyphenyl ethers, which are preferably water-soluble, water-miscible and/or oil-soluble, and polyglycols, especially polybutylene glycols, polypropylene glycols, polyethylene glycol and copolymers thereof, which are preferably water-soluble, water-miscible and/or oil-soluble; and silicone oils; and mixtures of two or more of these.

The term “complex esters” in the context of the invention is especially understood to mean esters that have been prepared using, for example, dicarboxylic acids (i.e. dibasic carboxylic acids) as well as monocarboxylic acids (i.e. monobasic carboxylic acids) and polyols.

In a particularly preferred embodiment of the lubricant composition of the invention, especially when the lubricant composition is used as gear oil, roller bearing oil and slide bearing oil for industry in general, the base oil is selected from polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, mineral oils, neopentyl glycol esters, pentaerythritol esters, trimethylolpropane esters and pentaerythritol and trimethylolpropane complex esters that are preferably as defined above, aliphatic carboxylic and dicarboxylic esters, triglyceride fatty acid (C8/C10) esters, alkylnaphthalenes, ethylene/α-olefin oligomers, and water-soluble, water-miscible and/or oil-soluble polyglycols, and mixtures of two or more of these.

It is especially preferable here when the base oil has NSF/H1 certification in order to enable use of the lubricant composition as gear oil, roller bearing oil and slide bearing oil for occasional unintentional contact with food in the food processing industry.

In another particularly preferred embodiment of the present invention, the base oil is selected from polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, farnesene-based oils, estolides and oil-soluble polyglycols, and mixtures of two or more of these. These base oils are advantageous with regard to their biodegradability (i.e. biodegradable for example according to OECD Test Guideline 301 A-F or OECD 306), and can accordingly contribute to improved biodegradability of the lubricant composition, such that these are especially suitable for applications as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

The amount of the base oil or base oil mixture in the lubricant composition is generally determined by the amount of the further constituent/components present in the composition, meaning that the lubricant composition is made up to 100% by weight by the base oil. The total amount of the base oil or base oil mixture is preferably at least 20% by weight, 30% by weight, 40% by weight, 50% by weight or 60% by weight.

Further preferably, the base oil or base oil mixture used in accordance with the invention has a viscosity of at least 5 mm²/s, more preferably of 5 mm²/s to 20 000 mm²/s, especially preferably of 5 mm²/s to 10 000 mm²/s, and very especially preferably of 5 mm²/s to 1700 mm²/s, in each case measured according to ASTM D 7042 at 40° C.

The lubricant composition of the invention additionally contains, as further constituent B), at least one additive as addition that improves a desired property of the lubricant. Customarily used additives or additions that are known in the prior art are antioxidants, antiwear additives, high-pressure additives, friction modifiers, anticorrosives, nonferrous metal deactivators, ion complex formers, solid lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators and defoamers, without being limited thereto.

In a preferred embodiment of the present invention, the lubricant composition therefore contains at least one additive selected from antioxidants, antiwear additives, high-pressure additives, friction modifiers, anticorrosives, nonferrous metal deactivators, ion complex formers, solid lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators and defoamers. More preferably, the lubricant composition contains an additive mixture of two or more additives selected from antioxidants, antiwear additives, high-pressure additives, friction modifiers, anticorrosives, nonferrous metal deactivators, ion complex formers, solid lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators and defoamers.

By virtue of the controlled addition of one or more additives, it is possible to achieve the effect that particular properties of the lubricant are improved and/or particular properties are imparted to the lubricant.

By virtue of the addition of antioxidants, it is possible to further improve the oxidation stability of the lubricant composition and hence to achieve an increase in (thermal) stability.

The antioxidants are preferably selected from, but are not limited to, the following compounds: amine compounds (aminic antioxidants), especially linear or branched aliphatic amine compounds and aromatic amine compounds and salts thereof, where the aliphatic and aromatic amine compounds may be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, phenol compounds (phenolic antioxidants); propionates; phosphites; sulfur compounds, especially sulfur-containing phenol compounds and sulfur-containing carboxylic acids, phosphorothionates, thiocarbamates, thiophosphates, and thiopropionates; and mixtures of these compounds.

Particularly preferred antioxidants are selected from aromatic diamines and secondary aromatic amines, phenolic resins, thiophenolic resins, phosphites, zinc thiocarbamate, zinc thiophosphate, butylated hydroxytoluene, butylated hydroxyanisole, phenyl-alpha-naphthylamines, phenyl-beta-naphthylamines, diphenylamine and diphenylamine derivatives, especially octylated diphenylamines, butylated diphenylamines and styrenized diphenylamines, quinoline and quinoline derivatives, naphthylamine and naphthylamine derivatives, di-alpha-tocopherol, di-tert-butylphenylpropanoic acid and esters thereof, and mixtures thereof.

Examples of antioxidants that are particularly suitable in accordance with the invention are benzeneamine-, N-phenyl-, reaction products with 2,4,4-trimethylpentene, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(4-(1,1,3,3-tetramethylbutyl)phenyl)amine, N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalene-1-amine, isomer mixtures of 90% to 97.5% C7 to C9 alkyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 2.5% to 10% methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], without being limited thereto.

Suitable antioxidants are commercially available.

In a particularly preferred embodiment of the lubricant composition of the invention, especially when the lubricant composition is used as gear oil, roller bearing oil and slide bearing oil for industry in general, the antioxidant is selected from phenolic antioxidants, aminic antioxidants, preferably linear or branched aliphatic amine compounds and aromatic amine compounds and salts thereof, where the aliphatic and aromatic compounds may be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, propionates and thiopropionates, very particular preference being given to aminic antioxidants, especially in the case of use of the lubricant composition as gear oil, slide bearing oil and roller bearing oil in the field of the food processing industry for occasional unintentional contact with food.

In another particularly preferred embodiment of the present invention, the antioxidant is selected from phenolic antioxidants, aminic antioxidants, preferably linear or branched aliphatic amine compounds and aromatic amine compounds and salts thereof, where the aliphatic and aromatic compounds may be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, phosphites, phosphorothionates and thiocarbamates, especially when the lubricant composition is used as gear oil, slide bearing oil and roller bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, very particular preference being given to aminic antioxidants.

According to the invention, the antioxidant used may be a single compound or a combination of two or more compounds.

In addition, the lubricant composition of the invention may contain one or more anticorrosives. The addition of anticorrosives can impart a corrosion- and rust-inhibiting effect to the lubricant composition.

Suitable anticorrosives, without being limited thereto, are preferably selected from the group of the acid salts, especially carboxylic acid metal salts, sulfonic acid metal salts, naphthalenesulfonic acid metal salts, benzenesulfonic acid metal salts, benzoic acid metal salts, naphthoic acid metal salts, naphthenic acid metal salts, succinic acid metal salts, salicylic acid metal salts and phosphoric acid metal salts, and derivatives thereof, including linear and branched aliphatic and aromatic derivatives of the acids/acid salts, which may additionally be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, with particular preference for sodium (Na), calcium (Ca), potassium (K) and magnesium (Mg) salts; amine, imine and imide compounds and metal salts thereof, especially linear and branched aliphatic amine, imine and imide compounds and aromatic amine, imine and imide compounds and metal salts thereof, where the aliphatic and aromatic amine, imine and imide compounds may be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, with particular preference for Na, Ca, K and Mg salts; and partly neutralized or non-neutralized dicarboxylic acid derivatives, such as succinic monoesters.

Suitable anticorrosives are commercially available.

When the lubricant composition is used as gear oil, slide bearing oil and roller bearing oil in the sector of the food processing industry for occasional unintentional contact with food, particular preference is given to the use of N-methylglycine or derivatives thereof (e.g. sarcosine) as anticorrosive.

In a particularly preferred embodiment of the lubricant composition of the invention, especially in the case of use of the lubricant composition as gear oil, roller bearing oil and slide bearing oil for industry in general and in the sector of the food processing industry for occasional unintentional contact with food, the anticorrosive is selected from the group of the carboxylic acid metal salts, sulfonic acid metal salts, benzenesulfonic acid metal salts, naphthalenesulfonic acid metal salts, benzoic acid metal salts and naphthoic acid metal salts and naphthenic acid metal salts, and derivatives thereof, including linear and branched, aliphatic and aromatic derivatives of the acid salts, which may additionally be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, with particular preference for Na, Ca, K and Mg salts; and partly neutralized or non-neutralized dicarboxylic acid derivatives, such as succinic monoesters.

In another particularly preferred embodiment of the present invention, the anticorrosive is selected from neutralized or neutral acid salts, preferably from neutral carboxylic acid, sulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, benzoic acid, naphthoic acid, naphthenic acid and phosphoric acid metal salts and derivatives thereof, including linear and branched, aliphatic and aromatic derivatives of the acid salts, which may additionally be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, and preferably the Na, Ca, K and Mg salts, with very particular preference for neutralized or neutral sulfonic acid, naphthalenesulfonic acid and benzenesulfonic acid metal salts, and especially the Ca salts, and greatest preference for neutral calcium sulfonates, especially when the lubricant composition is used as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media. One example of a particularly suitable anticorrosive in this embodiment is neutral alkylnaphthalenesulfonic acid calcium salts.

The anticorrosives may be used individually or in a combination of two or more.

“Neutral” or “neutralized” acid salts or metal salts in the context of the present invention are understood to mean acid salts or metal salts having a total acid number (TAN) of 30 mg KOH/g or lower.

In addition, the lubricant composition of the invention may contain one or more nonferrous metal deactivators and/or ion complexing agents.

By virtue of the addition of nonferrous metal deactivators and/or ion complexing agents, it is possible to protect non-iron metals, for example cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), tin (Sn), and zinc (Zn), which are among the so-called nonferrous metals, and alloys thereof, from corrosion by active sulfur.

Suitable nonferrous metal deactivators and ion complexing agents are preferably selected from triazole compounds, especially tolyltriazole, benzotriazole and derivatives thereof, imidazoline compounds, diazoles, mercaptothiadiazoles. Particular preferred nonferrous metal deactivators or ion complexing agents are triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof, with very particular preference for triazole compounds and derivatives thereof, especially benzotriazole and derivatives thereof, both in the case of use of the lubricant composition as gear oil, roller bearing oil and slide bearing oil for industry in general and in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media. According to the invention, it is possible to use the nonferrous metal deactivators or ion complexing agents individually or in a combination of two or more thereof.

Examples of particularly preferred nonferrous metal deactivators or ion complexing agents are benzotriazole and tolyltriazole and derivatives thereof, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, and a reaction mixture composed of N,N-bis(2-ethylhexyl)-6-methyl-1H-benzotriazole-1-methanamine, N,N-bis(2-ethylhexyl)-4-methyl-2H-benzotriazole-2-methanamine, N,N-bis(2-ethylhexyl)-5-methyl-2H-benzotriazole-2-methanamine, N,N-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methylamine and N,N-bis(2-ethylhexyl)-5-methyl-1H-benzotriazole-1-methylamine, without being limited thereto.

Suitable nonferrous metal deactivators or ion complexing agents are commercially available.

The lubricant composition of the invention may additionally contain one or more antiwear agents, friction modifiers and/or high-pressure additives. Suitable antiwear agents, friction modifiers and high-pressure additives are preferably selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, aryl thiophosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates, and mixtures of two or more of these, without being limited thereto. Suitable commercially available additives are, for example, the following products: IRGALUBE® TPPT, IRGALUBE® 232, IRGALUBE® 349, IRGALUBE® 353, IRGALUBE® 211 and ADDITIN® RC3760 Liq 3960, FIRC-SHUN® FG 1505 and FG 1506, NA-LUBE® KR-015FG, LUBEBOND®, FLUORO® FG, SYNALOX® 40-D, ACHESON® FGA 1820 and ACHESON® FGA 1810.

The lubricant composition of the invention may additionally contain one or more viscosity improvers. Suitable viscosity improvers are preferably selected from linear and branched, alkylated, acrylated and aliphatic polymers and copolymers, and polymerized fatty acid esters, and mixtures of two or more of these, without being limited thereto. Examples of suitable viscosity improvers are polymethacrylate, ethylene-propylene copolymer, polyisobutylene, polyalkylstyrene, hydrogenated styrene-isoprene copolymer. Suitable viscosity improvers can be purchased commercially.

The lubricant composition of the invention may additionally contain one or more UV stabilizers. Suitable UV stabilizers are preferably selected from nitrogen heterocycles and substituted nitrogen heterocycles, and mixtures of two or more of these, without being limited thereto. Suitable UV stabilizers can be purchased commercially.

The lubricant composition of the invention may additionally contain one or more solid lubricants. Suitable solid lubricants are preferably selected from PTFE, boron nitride, zinc oxide, magnesium oxide, pyrophosphates, thiosulfates, magnesium carbonates, calcium carbonate, calcium stearate, zinc sulfide, molybdenum sulfide, tungsten sulfide, tin sulfide, graphite, graphene, nanotubes, SiO₂ polymorphs, and mixtures of two or more of these, without being limited thereto. Suitable solid lubricants can be purchased commercially.

The lubricant composition of the invention may additionally contain one or more emulsifiers. Suitable emulsifiers are preferably selected from branched and/or linear, ethoxylated and propoxylated alcohols and salts thereof, especially alcohols having chain lengths of 14-18 carbon atoms, ethoxylated and/or propoxylated alkyl ethers, fatty acid esters, and ionic surfactants, for example sodium salts of alkylsulfonic acids, and mixtures of two or more of these, without being limited thereto. Suitable emulsifiers can be purchased commercially.

The lubricant composition of the invention may additionally contain one or more defoamers in order to prevent the formation of solid foams. Suitable defoamers are preferably selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, mono- and diglycerides of edible fats, acrylates, propoxylated and/or ethoxylated alkyl ethers, polyols including diols, and polysiloxanes, such as silicone oils or polydimethylsiloxanes, and mixtures of two or more of these, without being limited thereto. Defoamers that are particularly preferred in accordance with the invention are ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes, with very particular preference for polysiloxanes, both in the case of use of the lubricant composition as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, and in the case of use of the lubricant composition as gear oil, roller bearing oil and slide bearing oil for industry in general, and in the sector of the food processing industry for occasional unintentional contact with food. Suitable defoamers can be purchased commercially.

The lubricant composition of the invention may additionally comprise one or more color indicators. An example of a suitable color indicator is 2,5-thiophenediylbis(5-ter-butyl-1,3-benzoxazole), without being limited thereto. Suitable color indicators can be purchased commercially.

All additives may each be present in the lubricant grease composition of the invention as a single compound or any combination of two or more.

The total amount of all additives or additions in the lubricant composition is preferably 0.01% by weight or more, more preferably 0.025% by weight or more, for example 0.5% by weight or more, and 10% by weight or less, more preferably 7.5% by weight or less, for example 6% by weight or less, or 5% by weight or less, based on the overall lubricant composition.

For example, in embodiments of the invention that are especially suitable for use as gear oil, roller bearing oil and slide bearing oil for industry in general, including in the sector of the food processing industry for occasional unintentional contact with food, it is particularly preferable when the total amount of all additives is 0.01-7.5% by weight, most preferably 0.01-6.0% by weight, based on the total weight of the lubricant composition.

For example, in embodiments of the invention that are especially suitable for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, it is particularly preferable when the total amount of all additives is 0.5-7.0% by weight, most preferably 0.5-5.0% by weight, based on the total weight of the lubricant composition.

Since the additives serve to improve particular properties of the lubricant and/or to impart particular properties thereto, they may, according to the requirement or demand on the lubricant, be added thereto as a single substance or as a mixture of two or more additives, where the amount of the individual additives in an additive mixture is unlimited, provided that the above-defined total amount of all additives, based on the overall lubricant composition, is not exceeded.

In a preferred embodiment of the present invention, the lubricant composition contains

A) a base oil;

B) 0.01-10% by weight of the at least one additive, based on the total weight of the lubricant composition; and

C) 0.001-10% by weight, preferably 0.001-5% by weight, of the organic compound, based on the total weight of the lubricant composition,

where the constituents present add up to a total of 100% by weight and components A), B) and C) are as defined above.

In a further preferred embodiment of the invention, which is especially suitable for use as gear oil, roller bearing oil and slide bearing oil for industry in general including the sector of the food processing industry, the lubricant composition contains an additive mixture of two or more additives comprising one or more antioxidants, one or more antiwear and/or high-pressure additives, one or more defoamers, optionally one or more nonferrous metal deactivators, optionally one or more anticorrosives, and optionally a color indicator.

In a particularly preferred embodiment of the lubricant composition of the invention which is especially suitable for use as gear oil, roller bearing oil or slide bearing oil for industry in general, the lubricant composition contains

A) a base oil;

B) 0.01-7.5% by weight of an additive mixture, based on the total weight of the lubricant composition, where the additive mixture comprises one or more antioxidants, one or more antiwear and/or high-pressure additives, one or more defoamers, optionally one or more nonferrous metal deactivators, optionally one or more anticorrosives, and optionally a color indicator; and

C) 0.001-10% by weight, preferably 0.001-5% by weight, of the organic compound, based on the total weight of the lubricant composition,

where the constituents present add up to a total of 100% by weight and components A), B) and C) are as defined above.

In a very particularly preferred embodiment of the lubricant composition of the invention which is especially suitable for use as gear oil, roller bearing oil or slide bearing oil for industry in general, the lubricant composition contains

A) a base oil;

B) 0.01-6.0% by weight of an additive mixture, based on the total weight of the lubricant composition, where the additive mixture comprises:

one or more antioxidants, selected from phenolic antioxidants, aminic antioxidants, propionates and thiopropionates;

one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes;

one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates;

optionally one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof;

optionally one or more anticorrosives selected from the group of the carboxylic acid metal salts, sulfonic acid metal salts, naphthalenesulfonic acid metal salts, benzenesulfonic acid metal salts, benzoic acid metal salts, naphthoic acid metal salts and naphthenic acid metal salts and derivatives thereof, including linear and branched, aliphatic and aromatic derivatives of the acid salts, which may additionally be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, and especially the Na, Ca, K and Mg salts; and

optionally, as color indicator, 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole); and

C) 0.001-2.5% by weight of the organic compound, based on the total weight of the lubricant composition,

where the constituents present add up to a total of 100% by weight and components A) and C) are as defined above.

In this embodiment, the base oil is preferably selected from polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, mineral oils, neopentyl glycol esters, pentaerythritol esters, trimethylolpropane esters, and pentaerythritol and trimethylolpropane complex esters that are preferably as defined above, aliphatic carboxylic and dicarboxylic esters, triglyceride fatty acid (C8/C10) esters, alkylnaphthalenes, ethylene/α-olefin oligomers and water-soluble, water-miscible and/or oil-soluble, and mixtures of two or more of these.

Lubricants in this embodiment have high compatibility with respect to elastomers, such as FKM, NBR, HNBR, ACM/AEM and polyurethanes, which are typically used as seal materials. At the same time, lubricants in this embodiment show good tribological properties, such that they bring about an improvement in sliding characteristics, a reduction in the stick-slip effect, especially in friction contact at high load and at low bearing speeds and high load, and a positive influence on micropitting load-carrying capacity, and they are therefore especially suitable for use as gear oil, roller bearing oil and slide bearing oil for industry in general.

In a further embodiment of the present invention which is especially suitable for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, the lubricant composition contains, as additional constituent D), an ester compound, which also includes mixtures of two or more different ester compounds in accordance with the invention.

Preferably, in this embodiment, the at least one ester compound D) is selected from natural glyceride esters, especially from the group of sunflower oil, rapeseed oil or colza oil, linseed oil, corn oil, safflower oil, soybean oil, linseed oil, peanut oil, lesquerella oil, palm oil, olive oil, each of which may be in monomeric, oligomeric and/or polymerized form, and mixtures of the oils mentioned; and synthetic esters, especially from the group of polyol esters, polyol complex esters, complex esters of dimer acids, dimer acid esters, aliphatic carboxylic acid and dicarboxylic esters, phosphate esters and trimellitic and pyromellitic esters; and combinations thereof, particular preference being given to polyol esters and polyol complex esters, and especially to those polyol esters that are obtained by reaction of polyhydric alcohols (i.e. alcohols having more than one hydroxyl group) with monocarboxylic acids (i.e. monobasic carboxylic acids), and especially those polyol complex esters that are obtained by reaction of polyhydric alcohols with monocarboxylic acids and dicarboxylic acids (i.e. dibasic carboxylic acids) in any mixture, and combinations thereof.

It is preferable in this embodiment of the invention that the ester compound D) is biodegradable as per standard OECD 301 A-F or OECD 306, in order to achieve improved biodegradability and environmental compatibility of the lubricant composition of the invention.

It is additionally preferable that the at least one ester compound has a kinematic viscosity of at least 130 mm²/s at 40° C. More preferably, the kinematic viscosity of the at least one ester compound is in the range of 130-1500 mm²/s at 40° C., more preferably in the range of 130-1300 mm²/s at 40° C., in each case measured according to ASTM D 7042.

It is further preferable in this embodiment of the present invention that the ester compound is present in the lubricant composition in an amount of 0.1-85% by weight, more preferably of 5-85% by weight, especially preferably of 10-85% by weight, based on the total weight of the lubricant composition.

In a further-preferred embodiment of the present invention, the lubricant composition of the present invention contains:

A) a base oil;

B) 0.5-7% by weight of the at least one additive, based on the total weight of the lubricant composition;

C) 0.1-10% by weight of the organic compound, based on the total weight of the lubricant composition; and

D) 0.1-85% by weight of the ester compound, based on the total weight of the lubricant composition,

where the constituents present add up to a total of 100% by weight and components A), B), C) and D) are as defined above.

A lubricant of this composition, as well as high compatibility with respect to seal materials, especially elastomers, shows good sliding characteristics and simultaneously has good biodegradability, and is therefore especially suitable for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

The present invention therefore relates, in a further aspect, to a lubricant composition, especially for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, containing, as constituents:

A) a base oil;

B) 0.5-7% by weight of at least one additive;

C) 0.1-10% by weight of the organic compound comprising both a polar moiety and a nonpolar moiety; and

D) 0.1-85% by weight of an ester compound,

where the stated amounts are each based on the total weight of the lubricant composition and add up to a total of 100% by weight,

and where the organic compound has a relative permittivity ε_(r) in the range from 1.5 to 10, preferably from 1.7 to 8, especially preferably from 2 to 7, and most preferably from 2.3 to 5, and wherein a quotient ∫S₁/∫S₂ of the organic compound is in the range from 1 to 25, preferably from 1.3 to 22, especially preferably 1.7 to 17, and most preferably from 2 to 14, where “∫S₁” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and “∫S₂” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm¹ in an ATR spectrum of the organic compound.

Constituents A), B), C) and D) here are preferably as defined above.

More preferably, in this embodiment, the ester compound D) is selected from neopentyl glycol esters, trimethylolpropane esters and pentaerythritol esters that have especially been esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36, preferably C10-36, more preferably C14-C36, and most preferably C18-C36; and neopentyl glycol complex esters, trimethylolpropane complex esters and pentaerythritol complex esters that have especially been fully esterified or partly esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36, preferably C10-36, more preferably C14-C36, and most preferably C18-C36, and with saturated and/or mono- or polyunsaturated, linear and/or branched dicarboxylic acids of chain length C4-C36, preferably C4-C18, more preferably C4-C12, in any mixture (in other words, there are still free, unesterified hydroxyl groups); and combinations thereof.

These ester compounds are particularly preferred with regard to the biocompatibility or biodegradability of the lubricant composition.

Examples of particularly preferred ester compounds are pentaerythritol tetraisostearate, pentaerythritol isostearate sebacate complex esters, trimethylolpropane triisostearate, trimethylolpropane trioleate, trimethylolpropane tricaprylate, trimethylolpropane isostearate stearate sebacate complex esters, neopentyl diisostearate, without being limited thereto.

In addition, it is particularly preferable in this embodiment that the base oil is selected from oil-soluble polyglycols, polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, farnesene-based oils, estolides, and mixtures of two or more of these, very particular preference being given to oil-soluble polyglycols, polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs). These base oils have particularly advantageous properties with regard to their biodegradability (i.e. biodegradable, for example, according to OECD Test Guideline 301 A-F or OECD 306) and can accordingly contribute to improved biodegradability of the lubricant composition.

By virtue of a careful selection of additives optimized to the tribological system composed of elastomer material, lubricant and metal, it is possible to achieve a further improvement in the elastomer compatibility of the lubricant composition. Accordingly, it is preferable in this embodiment of the invention when the lubricant composition comprises an additive mixture comprising one or more antioxidants, nonferrous metal deactivators and anticorrosives, and optionally one or more defoamers and antiwear and/or high-pressure additives.

It is therefore particularly preferable in this embodiment of the invention that the at least one additive B) is an additive mixture comprising one or more antioxidants, nonferrous metal deactivators and anticorrosives, and optionally one or more defoamers and antiwear and/or high-pressure additives. The following have been found to be particularly advantageous in this regard:

Antioxidants selected from phenolic antioxidants, aminic antioxidants, preferably linear or branched aliphatic amine compounds and aromatic amine compounds and salts thereof, where the aliphatic and aromatic compounds may be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, phosphites, phosphorothionates and thiocarbamates, particular preference being given to aminic antioxidants;

Nonferrous metal deactivators selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof, particular preference being given to triazole compounds, especially benzotriazole compounds, and derivatives thereof;

Anticorrosives selected from neutralized or neutral carboxylic acid, sulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, benzoic acid, naphthoic acid, naphthenic acid and phosphoric acid metal salts, and derivatives thereof, preferably Na, Ca, K and Mg salts, particular preference being given to neutralized or neutral sulfonic acid, naphthalenesulfonic acid and benzenesulfonic acid metal salts, especially Ca salts, and very particular preference being given to neutral calcium sulfonates, such as neutral alkylnaphthalenesulfonic acid calcium salts;

Defoamers selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols including diols, acrylates and polysiloxanes, particular preference being given to polysiloxanes;

Antiwear and/or high-pressure additives selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates.

Such an additive mixture is particularly suitable for lubricant compositions for use as gear oil, roller bearing oil or slide bearing oil in the marine sector and in inland waterways and in machines and machine elements on land that may come into contact with water and/or aqueous media.

Also particularly preferred in this embodiment of the invention, therefore, is an additive mixture comprising:

one or more antioxidants, selected from aminic antioxidants, phenolic antioxidants, phosphites, phosphorothionates and thiocarbamates;

one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof;

one or more anticorrosives, selected from neutralized/neutral carboxylic acid, sulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, benzoic acid, naphthoic acid, naphthenic acid and phosphoric acid metal salts, and derivatives thereof, especially Na, Ca, K and Mg salts;

optionally one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes; and

optionally one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates.

A lubricant composition especially suitable for use as gear oil, roller bearing oil or slide bearing oil in the marine sector and in inland waterways and in machines and machine elements on land that may come into contact with water and/or aqueous media therefore contains, in a particularly preferred embodiment of the present invention:

A) a base oil;

B) 0.5-7% by weight of an additive mixture, based on the total weight of the lubricant composition, where the additive mixture comprises:

one or more antioxidants, selected from aminic antioxidants, phenolic antioxidants, phosphites, phosphorothionates and thiocarbamates;

one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof;

one or more anticorrosives, selected from neutralized/neutral carboxylic acid, sulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, benzoic acid, naphthoic acid, naphthenic acid and phosphoric acid metal salts, and derivatives thereof;

optionally one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes; and

optionally one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates;

C) 0.1-10% by weight of the organic compound, based on the total weight of the lubricant composition; and

D) 5-85% by weight of the ester compound, based on the total weight of the lubricant composition,

where the ester compound is selected from neopentyl glycol esters, trimethylolpropane esters and pentaerythritol esters that have especially been esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36, preferably C10-36, more preferably C14-C36, and most preferably C18-C36; and neopentyl glycol complex esters, trimethylolpropane complex esters and pentaerythritol complex esters that have especially been fully esterified or partly esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36, preferably C10-36, more preferably C14-C36, and most preferably C18-C36, and with saturated and/or mono- or polyunsaturated, linear and/or branched dicarboxylic acids of chain length C4-C36 preferably C4-C18, more preferably C4-C12, in any mixture; and combinations thereof;

where the base oil is selected from oil-soluble polyglycols, polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, farnesene-based oils, estolides, and mixtures of two or more of these,

and where the constituents present add up to a total of 100% by weight and constituent C) is as defined above.

It is especially preferable here that the additive mixture is very substantially neutral or has a minimum total acid number (TAN), since this has a particularly advantageous effect with regard to the elastomer compatibility of the lubricant compositions.

It is very particularly preferable in this embodiment of the invention that the lubricant composition contains:

A) a base oil, selected from oil-soluble polyglycols, polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs), and mixtures of two or more of these;

B) 0.5-5% by weight of an additive mixture comprising one or more aminic antioxidants, one or more neutralized/neutral sulfonic acid, naphthalenesulfonic acid and/or benzenesulfonic acid metal salts, one or more triazole compounds, especially benzotriazole compounds, and/or derivatives thereof, and one or more polysiloxanes;

C) 0.1-5% by weight of the organic compound; and

D) 10-85% by weight of pentaerythritol esters;

where the stated amounts are each based on the total weight of the lubricant composition and the constituents present add up to a total of 100% by weight, and the organic compound C) is as defined above.

A lubricant of this composition shows high compatibility with respect to seal materials, especially elastomers, and good sliding/lubrication properties. Moreover, a lubricant of this composition has good biodegradability, i.e. good biodegradability according to standard OECD 301 A-F or OECD 306, and low aquatoxicity (for example according to standard OECD 201, 202, 203 or 236), and is therefore especially suitable for use as gear oil, roller bearing or slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media.

The present invention therefore additionally provides a lubricant composition for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, comprising, as constituents:

A) a base oil, selected from oil-soluble polyglycols, polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs), and mixtures of two or more of these;

B) 0.5-5% by weight of an additive mixture comprising one or more aminic antioxidants, one or more neutralized/neutral sulfonic acid, naphthalenesulfonic acid and/or benzenesulfonic acid metal salts, one or more triazole compounds and/or triazole derivatives, and one or more polysiloxanes;

C) 0.1-5% by weight of the organic compound comprising both a polar moiety and a nonpolar moiety; and

D) 10-85% by weight of pentaerythritol esters.

where the stated amounts are each based on the total weight of the lubricant composition and the constituents present add up to a total of 100% by weight,

and where the organic compound has a relative permittivity ε_(r) in the range from 1.5 to 10, preferably from 1.7 to 8, especially preferably from 2 to 7, and most preferably from 2.3 to 5, and wherein a quotient ∫S₁/∫S₂ of the organic compound is in the range from 1 to 25, preferably from 1.3 to 22, especially preferably 1.7 to 17, and most preferably from 2 to 14, where “∫S₁” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and “∫S₂” denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm⁻¹ in an ATR spectrum of the organic compound.

In one embodiment, the lubricant composition of the invention is of excellent suitability for use as gear oils, roller bearing oils and slide bearing oil for industry in general, including as gear oil, roller bearing oil and slide bearing oil for occasional unintentional contact with foods.

General fields of use that are included in use as gear oils, roller bearing oils and slide bearing oil for industry in general comprise the lubrication of gears, especially spur, bevel, planetary, worm, hypoid and cycloid gears, hydraulics, linear guides, pneumatic components, instruments, bearings, especially slide and roller bearings, chains, cables, springs, propellers and compressors, and especially also of machine components and in systems that come into occasional unintentional contact with foodstuffs, without being limited thereto.

Chains consist of identical members joined to one another. They serve to transmit force and are used as drive chains, for example in motor vehicles, as control chains in automobile engines, as load chains in lock gates, or as transport chains in conveyor systems. Cables can be divided into running cables as encountered, for example, in cranes, winches and elevators, into stationary cables such as guy cables, and as support cables and sling cables. Screws are connecting elements that should be installed and deinstalled with minimum difficulty, and the materials used should not be damaged. Springs include leaf spring packs, cup spring packs, annular spring packs, helical cup springs and torsion springs. Instruments serve to regulate streams of solids, liquids and gases. In addition, they may also assume the function of adjusting, i.e. of mixing and controlling, one or more volume flows. As well as the typical applications as tap or mixing battery, all types of valves are also considered to be instruments.

Pneumatic components are pneumatic valves and cylinders which, by conversion of pneumatic to mechanical energy, create linear movements for pushing, lifting or retracting of workpieces and tools.

In hydraulics, force and torque are transmitted by means of pressure and volume flow. Examples are axial piston machines, external gear machines and radial piston motors.

The present invention therefore further provides for the use of the lubricant compositions of the invention as gear oil, roller bearing oil and slide bearing oil for industry in general, especially for lubrication of transmissions, such as spur, bevel, planetary, worm, hypoid and cycloid gears, hydraulics, linear guides, pneumatic components, instruments, bearings, such as slide and roller bearings, chains, cables, springs, propellers and compressors, and especially of machine components and in systems that come into occasional unintentional contact with foodstuffs, wherein the lubricant composition preferably comprises:

A) a base oil;

B) 0.01-10% by weight of the at least one additive, based on the total weight of the lubricant composition; and

C) 0.001-10% by weight of the organic compound, based on the total weight of the lubricant composition,

where the constituents present add up to a total of 100% by weight and components A), B) and C) are as defined above.

Particular preference is given to the use of a lubricant composition comprising:

A) a base oil;

B) 0.01-6.0% by weight of an additive mixture, based on the total weight of the lubricant composition, where the acid mixture comprises:

one or more antioxidants, selected from phenolic antioxidants, aminic antioxidants, propionates and thiopropionates;

one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes;

one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates;

optionally one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof;

optionally one or more anticorrosives selected from the group of carboxylic acid metal salts, sulfonic acid metal salts, naphthalenesulfonic acid metal salts, benzenesulfonic acid metal salts, benzoic acid metal salts, naphthoic acid metal salts and naphthenic acid metal salts and derivatives thereof, including linear and branched aliphatic and aromatic derivatives of the acid salts, which may additionally be substituted by one or more radicals selected from linear and/or branched alkyl radicals and aryl radicals, and especially the Na, Ca, K and Mg salts; and

optionally, as color indicator, 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole); and

C) 0.001-2.5% by weight of the organic compound, based on the total weight of the lubricant composition,

where the base oil is preferably selected from polyalphaolefins (PAOs), metallocene polyalphaolefins (mPAOs), white oils, mineral oils, neopentyl glycol esters, pentaerythritol esters, trimethylolpropane esters and pentaerythritol and trimethylolpropane complex esters that are preferably as defined above, aliphatic carboxylic and dicarboxylic esters, triglyceride fatty acid (C8/C10) esters, alkylnaphthalenes, ethylene/α-olefin oligomers and oil-soluble polyglycols, and mixtures of two or more of these,

and where the constituents present add up to a total of 100% by weight and the organic compound C) is as defined above,

as gear oil, roller bearing oil and slide bearing oil for industry in general and in the sector of the food processing industry for occasional, unintentional contact with food.

The lubricant composition of the invention, in a further embodiment, is additionally of excellent suitability for use as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways and in machines and machine elements on land that may come into contact with water and/or aqueous media.

Fields of use in the marine sector and in inland waterways especially include the lubrication of gears, hydraulics, bearings, such as slide, roller or stem tube bearings, propeller rudders, propeller shafts, pneumatic components linear guides, chains and cables in machines, machine components and installations that come into contact with saltwater in the marine sector, for example offshore installations, or with water and/or aqueous media in inland waterways, without being limited thereto.

In the marine sector, gears are used, for example, in thrusters and azipods. This use serves for transmission of force and conversion of force which takes place between drive and propeller. Both ingress of water into the interior and escape of lubricant into the marine environment is to be expected here.

A further application in the marine sector is that of jackup systems that jack up platforms, installation ships for wind turbines or oil rigs. This movement is accomplished by open gears.

Hydraulics in the marine sector serve to drive adjustable propeller rudders, and in fin stabilizers and rudder bearings. Linear guides are also used in the latter, which are usually lubricated with the same lubricant. Here too, lubrication takes place below the waterline. Accordingly, in this case too, ingress of water into machine parts and escape of lubricant into the marine environment is to be expected.

Slide bearing application in the marine sector primarily involves a propeller shaft bearing present in the stem tube, called the stem tube bearing. The primary function of the propeller shaft is the transmission of the driving motion through the ship's hull to the propeller. The bearing here ensures low-friction movement.

In addition, there is lubrication of machines and machine components in offshore wind turbines, oil and gas production platforms, in harbor installations, shipyards and the like that come into contact with seawater, water and aqueous media.

These also include chains that are used, for example, in lock gates, cables, such as rope or cables that are employed in nets, and instruments for control of flows of solids, liquids and gases. It is likewise necessary to lubricate propellers, springs and valves in a wide variety of different apparatuses and machines.

The present invention therefore further provides for the use of the lubricant composition of the invention as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways, especially for lubrication of transmissions, hydraulics, propeller rudders, propeller shafts, linear guides, pneumatic components, instruments, bearings such as slide, roller or stem tube bearings, chains, cables, springs and propellers in machines, machine components and systems that come into contact with saltwater in the marine sector or with water and/or aqueous media in inland waterways, and in machines and machine elements on land that may come into contact with water and/or aqueous media, wherein the lubricant composition preferably comprises:

A) a base oil;

B) 0.5-7% by weight of the at least one additive, based on the total weight of the lubricant composition;

C) 0.1-10% by weight of the organic compound, based on the total weight of the lubricant composition; and

D) 0.1-85% by weight of the ester compound, based on the total weight of the lubricant composition

where the constituents present add up to a total of 100% by weight and components A), B), C) and D) are as defined above.

Particular preference is given to the use of a lubricant composition comprising:

A) a base oil, selected from oil-soluble polyglycols, polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs), and mixtures of two or more of these;

B) 0.5-5% by weight of an additive mixture comprising one or more aminic antioxidants, one or more neutralized/neutral sulfonic acid, naphthalenesulfonic acid and/or benzenesulfonic acid metal salts, one or more triazole compounds and/or triazole derivatives, and one or more polysiloxanes;

C) 0.1-5% by weight of the organic compound; and

D) 10-85% by weight of pentaerythritol esters;

where the stated amounts are each based on the total weight of the lubricant composition and the constituents present add up to a total of 100% by weight, and where the organic compound C) is as defined above,

as gear oil, roller bearing oil and slide bearing oil in the marine sector and in inland waterways and in machines and machine elements on land that may come into contact with water and/or aqueous media.

The present invention is described in more detail by the nonlimiting examples that follow. The person skilled in the art will be able to prepare further compounds of the invention without exercising inventive skill.

EXAMPLES General Test Methods Used

The properties of the lubricant composition and of the components present therein, if not known from the manufacturer, are determined by means of the following methods:

-   -   Determination of viscosity: viscosity measurements are effected         according to ASTM D 7042 by means of a Stabinger SVM 3000         viscometer (Anton Paar).     -   Determination of acid number (TAN, total acid number [mg         KOH/g]):

In order to determine the acid number, the sample is dissolved in a solvent mixture and then, according to ASTM D 664-18E02, titrated with an alcoholic potassium hydroxide solution. The titration is conducted by potentiometry with the aid of a Solvotrode using a Metrohm 905 Titrando titration unit.

-   -   Determination of molecular weight (M_(n)):

Molecular weight is determined by means of GPC (gel permeation chromatography) against a polystyrene standard according to DIN 55672-1:2016-03 “Gel permeation chromatography (GPC)—Part 1: Tetrahydrofuran (THF) as elution solvent” using a SECcure GPC system.

-   -   Determination of the integrals ∫S₁ and ∫S₂:

ATR infrared spectroscopy measurements on the lubricity improvers are conducted in accordance with standard DIN 51451 (DIN 51451:2020-02) “Testing of petroleum products and related products—Analysis by infrared spectrometry—General working principles”, adapted to ATR measurement using a Bruker Tensor 27 IR spectrometer (OPUS 7.5 software) or Bruker Vertex 70 IR spectrometer (OPUS 7.0 software) from Bruker Optik GmbH.

The following regions in the ATR spectrum are used to form the integrals ∫S₁ and ∫S₂:

∫S₁: 3100-2750 cm⁻¹

∫S₂: 1800-1650 cm⁻¹

The procedure for formation of the baseline for both integrals is as follows:

The integral region is halved. In these two subregions, the respected absolute minima are determined. If there should be multiple absolute minimum points in a subregion, the point furthest within the boundary region of the overall integral is used. The baseline is calculated via a linear equation from the two absolute minimum points in the overall integral. The spectrum to be integrated is corrected using the baseline. This is followed by the integrating of the spectrum corrected by the baseline.

-   -   Determination of relative permittivity ε_(r):

In order to determine relative permittivity ε_(r), a laboratory instrument from the EPSILON+ system manufactured by flucon fluid control GmbH in accordance with standard DIN EN 60247 (DIN EN 60247:2005-01) “Insulating liquids—Measurement of relative permittivity, dielectric dissipation factor (tan δ) and d.c. resistivity”, the complex fluid impedance is determined. For each lubricity improver to be analyzed, after the sample has been introduced at room temperature (about 20° C.), a measurement is run with continuous data collection from about 18.5 to 21.5° C. (step 1) and back again (step 2). Subsequently, the data obtained at the instructed 20.0° C. from the two steps are compared and averaged.

Overview of Lubricity Improvers Used in the Examples (See Tables 1-A and 1-B):

TABLE 1-a Lubricity improver (GV) Trade name CAS number GV1 Ketjenlube ® 135 191744-19-1 GV2 Perfad ™ 3000 1392101-03-9 GV3 Lubrizol 87725 1654003-52-7 GV4 Herwemag OA 67701-08-0 GV5 Ilco Lube 2316 G 68424-61-3 Polyalphaolefin 6 (PAO 6) Durasyn ® 166 68037-01-4 (noninventive)

TABLE 1-b ATR ATR Lubricity spectrum spectrum Relative improver ∫ S₁ ∫ S₂ ∫ S₁/∫ S₂ permittivity ε_(r) GV1 180.67 71.87 2.51 3.98 GV2 226.03 25.71 8.79 4.60 GV3 234.42 25.57 9.17 2.39 GV4 203.99 64.91 3.14 2.50 GV5 190.71 48.81 3.91 4.75 PAO 6 249.84 0.40 626.36 2.12 (noninventive)

Production of the Lubricant Compositions:

The lubricant compositions are produced by a procedure known to the person skilled in the art, by mixing the base oils and additives in a suitable vessel, for example a mixing tank, using a suitable stirrer. Solid additives or components are brought into solution and stirred in by increasing temperature. Production can also be effected by means of continuous methods.

The following lubricant compositions of the invention are produced as described above (see table 2—examples 1-15b). As control, lubricant compositions without lubricity improvers (base formulation) are produced as described above (see table 2—comparative examples 1-5).

TABLE 2 Constituent (% by wt.) Ex. 1 Ex. 2 Ex. 3 Base oil 1 mPAO 65 (72.745) PE ester (68.31) mPAO 65 (73.548) Base oil 2 PAO 6 (14.35) PG (27.91) PAO 6 (14.397) Solubilizer TMP ester (10.00) — TMP ester (10.00) Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.50); Phenolic (0.30) Phenolic (0.30) Antiwear agent Amine phosphate — Amine phosphate (0.50); Phosphite (0.50); (0.50); Phosphite (0.50); TPPT (0.50) TPPT (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.09) mixture (0.095) Defoamer Silicone oil, dissolved Silicone-containing Silicone oil, dissolved in synthetic defoamer (0.1) in synthetic hydrocarbon (0.01) hydrocarbon (0.01) Anticorrosive — Neutral calcium — sulfonate (0.49) Lubricity GV 1 (0.50) GV 3 (3.0) GV 1 (0.25) improver Constituent (% by wt.) Ex. 4 Ex. 5 Ex. 6 Base oil 1 mPAO 150 (71.095) PE ester (68.31) mPAO 65 (73.045) Base oil 2 PAO 6 (16.00) PG (27.91) PAO 6 (14.35) Solubilizer TMP ester (10.00) — TMP ester (10.00) Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.50); Phenolic (0.30) Phenolic (0.30) Antiwear agent Amine phosphate — Amine phosphate (0.50); (0.50); Phosphite (0.50) Phosphite (0.50); TPPT (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.09) mixture (0.095) Defoamer Silicone-containing Silicone-containing Silicone oil, dissolved defoamer (0.01) defoamer (0.1) in synthetic hydrocarbon (0.01) Anticorrosive — Neutral calcium — sulfonate (0.49) Lubricity GV 2 (1.00) GV 5 (3.0) GV 1 (0.20) improver Constituent (% by wt.) Ex. 7 Ex. 8 Ex. 9 Base oil 1 mPAO 150 (71.095) PE ester (68.31) PE ester (68.31) Base oil 2 PAO 6 (16.00) PG (27.91) PG (27.91) Solubilizer TMP ester (10.00) — - Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.1) Phenolic (0.30) Antiwear agent Amine phosphate — — (0.50); Phosphite (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.09) mixture (0.09) Defoamer Silicone-containing Silicone-containing Silicone-containing defoamer (0.01) defoamer (0.1) defoamer (0.1) Anticorrosive — Neutral calcium Neutral calcium sulfonate (0.49) sulfonate (0.49) Lubricity GV 4 (1.00) GV 1 (3.0) GV 4 (3.0) improver Constituent (% by wt.) Ex. 10 Ex. 11 Ex. 12 Base oil 1 mPAO 150 (71.095) PE ester (68.31) mPAO 65 (73.148) Base oil 2 PAO 6 (16.00) PG (27.91) PAO 6 (14.347) Solubilizer TMP ester (10.00) — TMP ester (10.00) Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.50); Phenolic (0.30) Phenolic (0.30) Antiwear agent Amine phosphate — Amine phosphate (0.50); (0.50); Phosphite (0.50) Phosphite (0.50); TPPT (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.09) mixture (0.095) Defoamer Silicone-containing Silicone-containing Silicone oil, dissolved defoamer (0.01) defoamer (0.1) in synthetic hydrocarbon (0.01) Anticorrosive — Neutral calcium — sulfonate (0.49) Lubricity GV 1 (1.00) GV 2 (3.0) GV 1 (0.10) improver Constituent (% by wt.) Ex. 13 Ex. 14 Ex. 15 Base oil 1 mPAO 65 (73.148) PE ester (75.305) mPAO 150 (71.095) Base oil 2 PAO 6 (14.347) PG (20.90) PAO 6 (16.00) Solubilizer TMP ester (10.00) — TMP ester (10.00) Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.50); Phenolic (0.30) Phenolic (0.30) Antiwear agent Amine phosphate — Amine phosphate (0.50); (0.50); Phosphite (0.50); Phosphite (0.50) TPPT (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal deactivator derivative reaction derivative reaction derivative reaction mixture (0.095) mixture (0.095) mixture (0.095) Defoamer Silicone oil. dissolved Silicone-containing Silicone-containing in synthetic defoamer (0.1) defoamer (0.01) hydrocarbon (0.01) Anticorrosive — Neutral calcium — sulfonate (0.5) Lubricity GV 3 (0.10) GV 1 (3.0) GV 5 (1.00) improver Constituent (% by wt.) Ex. 15b Comp. ex. 1 Comp. ex. 2 Base oil 1 mPAO 65 (72.745) PE ester (70.43) mPAO 65 (73.148) Base oil 2 PAO 6 (14.60) PG (28.78) PAO 6 (14.347) Solubilizer TMP ester (10.00) — TMP ester (10.00) Antioxidant Aminic (0.50); Aminic (0.1) Aminic (0.50); Phenolic (0.30) Phenolic (0.30) Antiwear agent Amine phosphate — Amine phosphate (0.50); (0.50); Phosphite (0.50); Phosphite (0.50); TPPT (0.50) TPPT (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.1) mixture (0.095) Defoamer Silicone-containing Silicone-containing Silicone oil, dissolved defoamer (0.01) defoamer (0.1) in synthetic hydrocarbon (0.01) Anticorrosive — Neutral calcium — sulfonate (0.5) Lubricity GV 2 (0.25) — — improver Constituent (% by wt.) Comp. ex. 3 Comp. ex. 4 Comp. ex. 5 Base oil 1 PE ester (80.305) mPAO 150 (71.095) PE ester (68.31) Base oil 2 PG (18.90) PAO 6 (16.00) PG (27.91) Solubilizer — TMP ester (10.00) — Antioxidant Aminic (0.1) Aminic (0.50); Aminic (0.1) Phenolic (0.30) Antiwear agent — Amine phosphate — (0.50); Phosphite (0.50) Nonferrous Benzotriazole Benzotriazole Benzotriazole metal derivative reaction derivative reaction derivative reaction deactivator mixture (0.095) mixture (0.095) mixture (0.09) Defoamer Silicone-containing Silicone-containing Silicone-containing defoamer (0.1) defoamer (0.01) defoamer (0.1) Anticorrosive Neutral calcium — Neutral calcium sulfonate (0.5) sulfonate (0.49) Lubricity — — PAO 6 (3.0) improver

Example 16: Effect of Lubricity Improver on the Sliding Properties of Lubricants

In order to examine the effect of lubricity improver on the lubrication properties of lubricants, the change in transition speed at a white metal/steel contact surface is determined at low contact pressure. The transition speed is defined as the speed at which the contact surfaces can be fully separated, i.e. as the speed with which the transition from mixed friction (i.e. occasional contact of metallic friction partners/incompletely formed lubricant film) to the elastohydrodynamic (EHL) region (i.e. fully formed lubricant film and full separation of the metallic friction partners by lubricant film).

The tests are conducted using a tribometer (BALL-ON-DISK TRIBOMETER from AC²Tresearch/Austrian Competence Center for Tribology) with the cylinder-on-ring test combination. A 10×10 mm (diameter×length) 100Cr6 steel cylinder having a roughness Ra of about 0.02 μm, with application of a defined load, is rubbed against a white metal ring having a roughness Ra of about 1.3 μm. The white metal ring is in an oil reservoir.

By measurement of coefficients of friction by continuous variation of the speed of the white metal ring from low to high speed (0.05 m/s-2.5 m/s) and vice versa (2.5 m/s-0.05 m/s), Stribeck curves (friction-speed curves) are obtained.

Prior to commencement of the test, a running-in procedure was conducted. This included speed ramps from 0.05 m/s to 2.5 m/s and then from 2.5 m/s to 0.05 m/s at 10 N and 20 N at room temperature and at 10 N at 40° C.

The Stribeck curve is then generated at 20 N at 40° C. with a speed ramp from 0.05 m/s to 2.5 m/s.

FIG. 1 shows the measurement of the Stribeck curves for a base formulation without lubricity improver (comparative example 1) and a lubricant of the invention with lubricity improver (example 8). It is apparent that, in the presence of lubricity improver, there is a distinct movement in the transition speed to a lower speed (A to B).

FIG. 2 shows the transition speed of all lubricants tested. As apparent from FIG. 2 , all lubricants comprising lubricity improver that were tested (examples 2, 5, 8, 9, 11) have a distinctly lower transition speed than a base formulation (comparative example 1) and a lubricant composition comprising a noninventive lubricity improver (comparative example 5), which indicates that the lubricants of the invention comprising lubricity improver of the invention form the lubricant film much earlier than those of the comparative examples. The improved lubrication properties of the lubricants of the invention comprising lubricity improver show that they result in an improved load capacity, for example in slide bearings and similar components.

Example 17—Determination of Sliding Characteristics by Means of Elastomer-Dynamic Measurements

The tests are conducted by the test method of Hüttinger, Hermes, Wöppermann (Hüttinger, Hermes, Wöppermann, Prem (2015): Neues Prüfverfahren für dynamische Dichtungen von Getriebemotoren [New Test Method for Dynamic Seals of Drive Motors]. In: Berger and Kiefer (eds.) Dichtungstechnisches Jahrbuch 2016, Mannheim: Isgatec) on a test bed in accordance with DIN 3761-10:1984-10 (Beuth (publisher): DIN 3761, Rotary shaft lip type seals for automobiles, 1984).

The conditions/measurement parameters are chosen as follows: elastomer material: 75 FKM 585; pressure: 0.25 bar; temperature: 70° C.; test duration: 240 h; 10 cycles with speed of 2000 rpm (20 h) and 0 rpm (4 h); grease applied: Bremer & Leguil Cassida GTS 2.

By means of elastomer-dynamic measurements on FKM radial shaft sealing rings from Freudenberg BAU3 38-90-12 75FKM585 (Art. 49385291/49370995) by the above-described test method, dynamic elastomer compatibility with use of lubricant compositions of the invention (examples 3 and 15b) is determined. This is followed by measurement of wear scar width and of shaft wear, which are a measure of the sliding characteristics or elastomer compatibility of the lubricant composition. The control uses a base formulation without lubricity improver (comparative example 2).

The results of the measurements are summarized in table 3:

TABLE 3 A-RWDR-BAU3 38-90-12 75FKM585 (Art. 49385291/49370995) 70° C. Ex. 3 Ex. 15b Comp. ex. 2 Comp. ex. 4 Wear scar width/max. 0.35 0.54 0.66 0.75 value [mm] Shaft wear [μm] 0 14 20 30

The test results show that, in the case of the lubricant compositions of the invention comprising lubricity improver (example 3: GV 1; example 15b: GV 2, each by comparison with comparative example 2), a reduction in radial shaft sealing ring wear scar width from 0.66 mm to 0.35 mm (example 3) or 0.54 mm (example 15b) and a reduction in shaft wear from 20 μm to 0 μm (example 3) or 14 μm (example 15b) by comparison with the base formulation without lubricity improver (comparative example 2) is achieved. As shown by the test results for comparative example 4, by contrast, increasing the viscosity of the base formulation (mPAO 150/comparative example 4 compared to mPAO 65/comparative example 2) does not achieve any improvement.

Example 18—Determination of Sliding Characteristics in the Case of Elastomer as Friction Partner by Means of Des (Dynamic Elastomer Screening)

The tests are conducted with a “ring-on-disk tribometer” with development of the construction described by Sommer M. and Haas W. ([1] Sommer, M., Haas, W. “A new approach on grease tribology in sealing technology: Influence of the thickener particles”, Tribology International (2016), 103, 574-583). The test material used is FKM elastomer material. The counterpart is a steel counterpart.

The lubricant composition to be analyzed is examined in a ring-on-disk tribometer as described in [1] at a constant speed of 1.5 m/s and a temperature of 60° C. at a linear load of 0.90 N/mm in order to provoke collapse of the lubricant film and solid-state contact in the case of poor lubricant film formation.

As can be inferred from FIGS. 3A to 3D, the lubricant compositions of the invention comprising lubricity improver (example 2: GV 3; example 5: GV 5; example 11, GV 2; example 14; GV 1) show a much calmer and slower progression of the coefficient of friction p over time, which means a stable lubricant film structure and suggests hydrodynamic lubrication. This suggests a more stable tribological system of elastomer/lubricant/steel counterpart with lower wear (see FIGS. 4A, 4B). The base formulation without lubricity improver (comparative example 3) shows an unstable lubricant film structure, which is manifested in significant variation and a higher level of the coefficient of friction. This suggests at least local solid-state contact and a marked stick-slip effect.

As shown in FIGS. 4A and 4B, addition of the lubricity improver reduces wear on the elastomer body by 57% (example 2: GV 3), 50% (example 14, GV 1), 67% (example 11, GV 2) or 63% (example 5, GV 5), and reduces wear on the steel counterpart by 80% (example 2: GV 3), 67% (example 14: GV 1), 67% (example 11: GV 2) or 73% (example 5: GV 5), each by comparison with the base formulation without lubricity improver (comparative example 3).

Example 19: Effect of the Lubricity Improver on Resistance to Micropitting

Resistance to micropitting is examined in a micro-pitting resistance (MPR) testbed (PCS Instruments, London, UK). Micropitting refers to damage at gear contacts.

The testbed uses a triple configuration in which a central roll is in contact with three disks, which leads to three roll contact cycles per roll rotation. The two lower disks are partially immersed in oil and transport it into the contact during the test, which simulates splash lubrication. The roll and the disks are driven by separate motors, which permits the simulation of different slide-roll ratios (SRR). The tests are conducted at a Hertzian contact pressure of 1.7 GPa, an SRR of 20% to 30%, an oil temperature of 90° C. and 10 million cycles. The coefficient of friction and vibration were recorded during the test with a torque gauge or an acceleration gauge. At the end of the test, the test roll is cleaned using a solvent in order to remove residual oil, and the weight of the roll is determined, and images of the wear scar are taken with an optical microscope. The capacity of a lubricant composition with regard to its resistance to micropitting is assessed by the loss of weight (comparison of weight before and after measurement) of the roll (see FIG. 5A) and by the change in wear scar width (see FIG. 5B).

The results of the MPR measurements from FIG. 5A show that, in the case of the lubricant compositions of the invention comprising lubricity improver (see examples 1, 4, 6, 12), a distinct reduction in weight loss compared to a base formulation without lubricity improver (see comparative example 2) is apparent.

The results of the MPR measurements from FIG. 5B show that, in the case of the lubricant compositions of the invention comprising lubricity improver (see examples 4, 7, 10, 15), a distinct reduction in wear scar width compared to a base formulation without lubricity improver (see comparative example 4) is apparent.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C. 

1: A lubricant composition comprising: A) a base oil; B) at least one additive; and C) 0.001-10% by weight, based on the total weight of the lubricant composition, of an organic compound comprising both a polar moiety and a nonpolar moiety, as lubricity improver, wherein the organic compound has a relative permittivity ε_(r) in the range from 1.5 to 10, and a quotient ∫S₁/∫S₂ for the organic compound is in the range from 1 to 25, wherein ∫S₁ denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 3100-2750 cm⁻¹ in an ATR spectrum of the organic compound, and ∫S₂ denotes the sum total of the area(s) of the IR absorption band(s) in the wavenumber range of 1800-1650 cm⁻¹ in an ATR spectrum of the organic compound. 2: The lubricant composition as claimed in claim 1, wherein the amount of the organic compound is 0.001-5% by weight, based on the total weight of the lubricant composition. 3: The lubricant composition as claimed in claim 1, wherein the amount of the at least one additive is 0.01-10% by weight, based on the total weight of the lubricant composition. 4: The lubricant composition as claimed in claim 1, wherein the at least one additive is selected from antioxidants, antiwear additives, friction modifiers, high-pressure additives, anticorrosives, nonferrous metal deactivators, ion complex formers, solid-state lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators and defoamers. 5: The lubricant composition as claimed in claim 1, comprising: A) the base oil; B) 0.01-10% by weight of the at least one additive, based on the total weight of the lubricant composition; and C) 0.001-5% by weight of the organic compound, based on the total weight of the lubricant composition, where the constituents present add up to a total of 100% by weight. 6: The lubricant composition as claimed in claim 1, wherein the at least one additive is an additive mixture comprising one or more antioxidants, one or more antiwear and/or high-pressure additives, one or more defoamers, optionally one or more nonferrous metal deactivators, optionally one or more anticorrosives, and optionally a color indicator. 7: The lubricant composition as claimed in claim 1, comprising: A) the base oil; B) 0.01-6.0% by weight of the at least one additive, based on the total weight of the lubricant composition, wherein the at least one additive is an additive mixture comprising: one or more antioxidants, selected from phenolic antioxidants, aminic antioxidants, propionates and thiopropionates; one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes; one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO2, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates; optionally one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof; optionally one or more anticorrosives selected from the group of the carboxylic acid metal salts, sulfonic acid metal salts, naphthalenesulfonic acid metal salts, benzenesulfonic acid metal salts, benzoic acid metal salts, naphthoic acid metal salts, naphthenic acid metal salts and N-methylglycine, and derivatives thereof; and optionally, as color indicator, 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole); and C) 0.001-2.5% by weight of the organic compound, based on the total weight of the lubricant composition, where the constituents present add up to a total of 100% by weight. 8: The lubricant composition as claimed in claim 1, wherein the lubricant composition comprises an ester compound as additional component D). 9: The lubricant composition as claimed in claim 8, wherein the ester compound is selected from natural glyceride esters, polyol esters, polyol complex esters, dimer acid esters and dimer acid complex esters, aliphatic carboxylic and dicarboxylic esters, trimellitic and pyromellitic esters, and phosphate esters, and mixtures of two or more of these. 10: The lubricant composition as claimed in claim 8, wherein the amount of the ester compound is 0.1-85% by weight, based on the total weight of the lubricant composition. 11: The lubricant composition as claimed in claim 8, wherein the lubricant composition comprises: A) the base oil; B) 0.5-7% by weight of the at least one additive, based on the total weight of the lubricant composition; C) 0.1-10% by weight of the organic compound, based on the total weight of the lubricant composition; and D) 0.1-85% by weight of the ester compound, based on the total weight of the lubricant composition where the constituents present add up to a total of 100% by weight. 12: The lubricant composition as claimed in claim 8, wherein the ester compound is selected from neopentyl glycol esters, trimethylolpropane esters and pentaerythritol esters that have been esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36; and neopentyl glycol complex esters, trimethylolpropane complex esters and pentaerythritol complex esters that have been fully esterified or partly esterified with saturated and/or mono- or polyunsaturated, linear and/or branched monocarboxylic acids of chain length C4-C36 and with saturated and/or mono- or polyunsaturated, linear and/or branched dicarboxylic acids of chain length C4-C36 in any mixture; and mixtures of two or more of these. 13: The lubricant composition as claimed in claim 8, wherein the base oil is selected from oil-soluble polyglycols, poly alphaolefins, metallocene polyalphaolefins, white oils, mineral oils, farnesene-based oils, estolides, and mixtures of two or more of these. 14: The lubricant composition as claimed in claim 8, wherein the at least one additive is an additive mixture comprising: one or more antioxidants, selected from aminic antioxidants, phenolic antioxidants, phosphites, phosphorothionates and thiocarbamates; one or more nonferrous metal deactivators, selected from triazole compounds, salicylates and mercaptothiadiazoles, and derivatives thereof; one or more anticorrosives, selected from neutral carboxylic acid, sulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, benzoic acid, naphthoic acid, naphthenic acid and phosphoric acid metal salts, and N-methylglycine and derivatives thereof; optionally one or more defoamers, selected from ethoxylated and/or propoxylated alcohols having chain lengths of 10-18 carbon atoms, polyols, acrylates and polysiloxanes; and optionally one or more antiwear and/or high-pressure additives, selected from amines, amine phosphates, branched and/or linear alkylated phosphates, phosphites, thiophosphates, and phosphothionates, aryl phosphates, alkylated polysulfides, sulfonated amine compounds, sulfonated fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al₂O₃, SiO₂, TiO₂, ZrO₂, WO₃, Ta₂O₅, V₂O₅, CeO₂, aluminum titanate, BN, MoSi₂, SiC, Si₃N₄, TiC, TiN, ZrB₂, clay minerals and mixtures thereof, sulfonic salts, and thermally stable carbonates and sulfates. 15: The lubricant composition as claimed in claim 8, comprising A) the base oil, wherein the base oil is selected from oil-soluble polyglycols, polyalphaolefins and metallocene polyalphaolefins, and mixtures of two or more of these; B) 0.5-5% by weight of the at least one additive, wherein the at least one additive is an additive mixture comprising one or more aminic antioxidants, one or more neutral sulfonic acid, naphthalenesulfonic acid and/or benzenesulfonic acid metal salts, one or more triazole compounds and/or derivatives thereof, and one or more polysiloxanes; C) 0.1-5% by weight of the organic compound; and D) 10-85% by weight of the ester compound, wherein the ester compound is pentaerythritol esters; where the stated amounts are each based on the total weight of the lubricant composition and the constituents present add up to a total of 100% by weight. 16: A system comprising the lubricant composition as claimed in claim 1, wherein the system is selected from a gear, a bearing, a transmission, hydraulics, a linear guide, a pneumatic component, an instrument, a chain, a cable, a spring, a propeller, a compressor, and a machine component, optionally wherein the system is configured to come into occasional unintentional contact with foodstuffs. 17: A system comprising the lubricant composition as claimed in claim 1, wherein the system is selected from a gear, a bearing, a transmission, hydraulics, a propeller rudder, a propeller shaft, a linear guide, a pneumatic component, an instrument, a chain, a cable, a spring, a propeller, a machine, and a machine component, optionally wherein the system is configured to come into contact with saltwater in the marine sector, with water and/or aqueous media in inland waterways, or with water and/or aqueous media when the system is on land. 18: The system of claim 16, wherein the gear is selected from spur, bevel, planetary, worm, hypoid, and cycloid, and/or the bearing is selected from slide and roller. 19: The system of claim 17, wherein the bearing is selected from slide, roller, and stem tube. 